Oral mucosal defects are secondary to oncologic resection, traumatic events or congenital craniofacial malformations such as cleft palate. Current repair treatments such as autologous grafts are restricted by donor site morbidity, tissue shortage, and retention of the original characteristics of the donor tissue. AlloDerm, a native acellular dermal matrix, with an intact basement membrane, is currently used as a dermal oral soft tissue graft, however, a second procedure for epithelial grafting is required. Keratinocyte populated acellular dermal substrates in ex vivo produced oral mucosal equivalents have been proposed, however, the low cell number obtained from harvested tissue results in graft failure. The proposed research studies will address the capacity of bone marrow-derived mesenchymal stem cells (MSC) to regenerate the oral mucosa epithelium by mimicking an environment in vitro similar to that seen in the human body. Bone marrow- derived mesenchymal stem cells (MSC) are capable of self-renewal, differentiation into cell phenotypes of mesodermal lineage, and transdifferentiation into other cell lineages including epithelial cells. Their local microenvironment composed of growth factors and extracellular matrix (ECM) is known to play a critical role in controlling the proliferation and differentiation fate of stem cells. Our hypothess is that tissue-specific extracellular matrix provides a native microenvironment that governs the ability of multipotent stem cells seeded on Alloderm to both self-renew and differentiate into functional full-thickness oral mucosa epithelium. The following specific aims will be proposed to test this hypothesis: 1) Determine the capacity of MSCs maintained on tissue-specific microenvironment to differentiate into an epithelial cell lineage and form oral mucosa epithelium in vitro; 2) Demonstrate the capacity of predifferentiated MSCs maintained on AlloDerm for oral mucosa epithelium regeneration in vivo using an athymic nude mouse model. These studies will provide training in stem cell maintenance and differentiation, quantitative gene expression, immunochemistry, flow cytometry, FACS sorting, animal modeling, and cell culture. This study is innovative because human bone marrow-derived MSC capability to transdifferentiate into epithelial cells for engineering oral mucosa epithelium has not been explored. The proposed research is significant because it will facilitate the optimization of in vitro oral mucosa equivalnt models for studies of oral mucosa biology and pathology as well as a model alternative to animals for testing of consumer products. These findings will have an impact by initiating human bone marrow-derived MSC research exploration of the field of craniofacial regenerative medicine and lay the foundation to further study the molecular complexity and dynamics of native and tissue-specific ECM in the regulation of MSC proliferation, survival, and differentiation. A better understanding of these mechanisms will move the field closer to bone marrow-derived MSC based therapeutic application by utilizing bone marrow- derived MSCs as an unlimited source of stem cells and treatment of craniofacial defects. Through these studies, I will acquire state-of-the-art knowledge and skills toward my goal to become an established dentist- scientist.